The spatial pattern of neuroretinal rim loss in ocular hypertension.

PURPOSE: To assess the spatial pattern of rim area (RA) decline in ocular hypertension (OHT) as measured with the Heidelberg Retina Tomograph (HRT; Heidelberg Engineering, Heidelberg, Germany).

METHODS

One hundred ninety-eight OHT subjects were examined with the HRT from 1993 to 2001. One eye per subject was selected for analysis, with a median of 10 (range, 5-16) mean topographies, analyzed using the Moorfields Reference Plane. Linear regression of RA/time was performed for each sector; temporal (T), superotemporal (ST), inferotemporal (IT), nasal (N), superonasal (SN), and inferonasal (IN). The mean slope of RA loss (expressed as square millimeters per year and the percentage of baseline RA/year) and the frequency of significant negative slopes were compared in each sector.

RESULTS

The steepest mean slopes of RA loss were observed in the IT sector (-1.43%/y) followed by ST (-1.05%/y), SN (-0.52%/y), IN (-0.46%/y), N (-0.31%/y), and T (0.33%/y). Significant negative slopes (P < 0.01) were observed most frequently in the ST sector (12%) followed by IN (10%), IT (10%), N (7%), SN (6%), and T (2%).

CONCLUSIONS

The rate of RA loss (%/y) was greatest in the IT and ST sectors. However, because the nasal sectors contain more blood vessels (included in the HRT RA measurement), the percentage loss of neural tissue is underestimated in these sectors, to an unknown extent. The frequency of significant negative RA loss slopes was greatest in the ST, IN, and IT sectors. The finding suggests that all disc sectors should be evaluated for glaucomatous change in ocular hypertensive eyes.